Vibration issues

[sasjzl]

I have never really worried about vibration until tonight. All of a sudden at about 8k rpm I have this really bad vibration that I have never experienced before. This is after truing up the piece. Now that I am more sensitive to vibration I can tell that there is still vibration below 8k but much less obvious. What I am wondering is, is there a way to locate or at least narrow down the source of the vibration? It is a Harbor Freight 34706 with four bags of 60lb cement on a shelf I made below the lathe. So there are 240 lbs of ballast on there but I have never gone to the trouble of leveling the lathe. I am hoping to do that tomorrow and would be glad to hear any tips or hints on that.

Also, I should include a picture but when you see lines in your work when you are cutting as sharp and smoothly as you can is it possible that the lines are coming from low level vibration of the lathe?

Thanks very much,
Jim Lee

 

[Trent Mason]

Jim, I have the same lathe and the only time I really encounter vibration is when I'm making deep cuts, hollowing out the inside of a bowl. I'm not sure what it is. Could be that the blank came off center or a problem with the machine. That's a great idea to put concrete bags on the bottom shelf.

 

[HLW]

Did I understand correctly that your lathe vibrates at 8k or was it 800 rpm's? I don't own an HF lathe but does it vibrate with or without with just the face plate on the lathe? If so, I would check the bearing on the head stock pulley shaft. Just thought it would be a good place to start looking. Maybe some of the other HF owners can advise? Good luck.

 

[sasjzl]

Thanks Trent. Unfortunately I have already added the 240 lbs of sandbags on a shelf I made when I first got it. I think I am going to try some serious leveling on the bottom of the feet to make sure that all legs are touching at the same time with a similar weight. Do you not have any weight on your 34706? That would be my nightmare if there is something on the lathe which has gone bad to cause the vibration...which appears to be new.

By the by, do you find your lathe underpowered? I find it way too easy to stop the lathe.

Thanks,
Jim Lee

 

[sasjzl]

"Did I understand correctly that your lathe vibrates at 8k or was it 800 rpm's? I don't own an HF lathe but does it vibrate with or without with just the face plate on the lathe?"

It starts vibrating badly at about 8k rpm's. This is without the faceplate or a chuck. Just between centers using a four pronged spur center and the piece is all trued up.

Thanks,
Jim Lee

 

[erasmussen]

How long and thick is the piece it could be whipping

 

[sasjzl]

It's a trued log hoping to be a hollow form. About 14" long and 6" thick. A pretty solid piece of maple (I think).

Thanks,
Jim Lee

 

[CrealBilly]

It's a dang shame you can turn anything on that lathe without it wanting to walk out the door.

 

[erasmussen]

And your turning it at 8k, wow
My lathe will only go to about 2k top end flat out

 

[HLW]

Erasmussan,That's why I asked in my other response if he meant 800 rpms rather than 8k. My Nova will only turn 2300 rpm"s max and I've never turned anything that fast. Sasjzl if your lathe will turn 8,000 rpm's and not vibrate until that point my guess is you don't have a problem and it's balanced pretty well. As for me, I don't want to be standing or turning anywhere near a wood lathe that turns 8,000 rpm's.:nah:

 

[Trent Mason]

"Did I understand correctly that your lathe vibrates at 8k or was it 800 rpm's? I don't own an HF lathe but does it vibrate with or without with just the face plate on the lathe?"

It starts vibrating badly at about 8k rpm's. This is without the faceplate or a chuck. Just between centers using a four pronged spur center and the piece is all trued up.

Thanks,
Jim Lee

Jim,

HF = Harbor Freight. I have the 34706, as does Earl. If you're turning a log like that, my first guess is that it is off center, or that the log is oddly shaped or that it doesn't have uniform density. I had that happen turning a bowl of claro walnut. One side of it was a lot denser and it gave me a beating I'll never forget. :swoon: If you find that it is very easy to stall your lathe, you might have an issue with the motor. The same thing happened to me on my first 34706. I'd barely touch the wood and it would stall. Turned out to be a bad motor. I took it back and exchanged it for a new one. :thumbs_up

 

[sasjzl]

Foolish error on my part. I have a dial that goes from 1-10 and it is when I am at 8 that the vibration gets really bad. For some reason I did the translation from "8" on this arbitrary scale to "8k". I would probably have a holes in my garage wall and ceiling if it went up to 8k. I'm like the guy in Spinal Tap who turned the amp up to 11.

Trent, I just replaced the motor at Harbor Fright. It is exactly the same as it was before. Maybe I have had two bad motors.

Thanks,
Jim Lee

 

[FredP]

I get vibration on my PM sometimes. depends on the piece and the speed. when a piece starts to vibrate it means slow down a little.:gar-Bi usually when i dont pay attention to it the next sound is BANG!:rotflm: then it's duck an run time. you realy dont need to run the lathe that fast [I know we all do] but with variable speed I listen to the machine. when it says "thats too fast" I slow it down till the noise goes away. it's that simple.

 

[CarvedTones]

I have wondered about the issue of vibration coming and going and different RPMs. I have a VS lathe and there are times I can limit vibration by going just a little faster or slower. Slower I understand, but it is a real head scratcher as to why it sometimes seems to be better balanced at a higher speed (but less than 8k ).

 

[CrealBilly]

usually when i dont pay attention to it the next sound is BANG!:rotflm: then it's duck an run time.

Yep a wise investment would be a full hockey players goalie suit.

 

[FredP]

I have wondered about the issue of vibration coming and going and different RPMs. I have a VS lathe and there are times I can limit vibration by going just a little faster or slower. Slower I understand, but it is a real head scratcher as to why it sometimes seems to be better balanced at a higher speed (but less than 8k ).

yep sometimes faster relieves it too. something to do with harmonic distortion?:dontknow: I dont know but listening to the wood and the machine is all part of the process.:icon_thum

 

[Gunslinger]

An idea I’ve used from a Lyle Jamieson video for leveling.
Two diagonal legs (of the four legs) are planted firmly on the ground by default.
Mount your blank and increase the speed until vibration sets in. He did not say to do it but I used a very thin scraper (paint) to try to slide under one of the front legs. It seemed solid so I went to the other end and it would slide under slightly. With the lathe running adjust that foot until the vibration decreases. Note: If you go to far you may place the other two diagonal legs off balance. It made quite a bit of difference with my lathe.
Mike

 

[boxxmaker]

Hey Harold,better check your speeds out again.That sucker will crank up about 3600 hundred rpms :gar-La; Just had ta say that.
I have about 600 lbs on my stand.One of the reasons you will get viberations with the cheaper lathes is that the frame work is not that solid,compaired to the bigger lathes.If your piece is well rounded when you start turning,you shouldn't get to much that much vibs.I can turn a 16" blank at over 1000 rpms without any vibs,but that is with the tail stock up against the piece.

Erasmussan,That's why I asked in my other response if he meant 800 rpms rather than 8k. My Nova will only turn 2300 rpm"s max and I've never turned anything that fast. Sasjzl if your lathe will turn 8,000 rpm's and not vibrate until that point my guess is you don't have a problem and it's balanced pretty well. As for me, I don't want to be standing or turning anywhere near a wood lathe that turns 8,000 rpm's.:nah:

 

[DaveD]

Some info on recommended speeds
http://www.woodturnerscatalog.com/woodturners/Images/safe_lathe_speeds.pdf

page 4 of this one
http://content.wmhtoolgroup.com/manuals/m_708359.pdf

 

[sasjzl]

I am still ruminating on vibration. Did not get a chance to try out levelers today but really hope to tomorrow.

Has anyone had any luck with either levelers on the feet of their lathe or rubber pads to lessen vibration? This vibration I have is surely not a show stopper but I am really curious. As far as I can tell this is happening on well trued (as best as I can) up bowl blanks at various stages. Nothing serious before I turn it up to 8 on my dial that goes to 10. Probably about 2k rpm? But I can still feel some subtle vibration before it really kicks in.

Thanks very much,
Jim Lee